/*
 *  UPCEReader.cpp
 *  ZXing
 *
 *  Created by Lukasz Warchol on 10-01-26.
 *  Copyright 2010 ZXing authors All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "UPCEReader.h"
#include <zxing/ReaderException.h>

namespace zxing {
	namespace oned {
		
		/**
		 * The pattern that marks the middle, and end, of a UPC-E pattern.
		 * There is no "second half" to a UPC-E barcode.
		 */
		static const int MIDDLE_END_PATTERN[6] = {1, 1, 1, 1, 1, 1};
		
		/**
		 * See {@link #L_AND_G_PATTERNS}; these values similarly represent patterns of
		 * even-odd parity encodings of digits that imply both the number system (0 or 1)
		 * used, and the check digit.
		 */
		static const int NUMSYS_AND_CHECK_DIGIT_PATTERNS[2][10] = {
			{0x38, 0x34, 0x32, 0x31, 0x2C, 0x26, 0x23, 0x2A, 0x29, 0x25},
			{0x07, 0x0B, 0x0D, 0x0E, 0x13, 0x19, 0x1C, 0x15, 0x16, 0x1A}
		};
		
		UPCEReader::UPCEReader(){}
		
		int UPCEReader::decodeMiddle(Ref<BitArray> row, int startRange[], int startRangeLen, std::string& resultString){
			const int countersLen = 4;
			int counters[countersLen] = { 0, 0, 0, 0 };
			
			int end = row->getSize();
			int rowOffset = startRange[1];
			
			int lgPatternFound = 0;
						
			for (int x = 0; x < 6 && rowOffset < end; x++) {
				int bestMatch = decodeDigit(row, counters, countersLen, rowOffset, UPC_EAN_PATTERNS_L_AND_G_PATTERNS);
				resultString.append(1, (char) ('0' + bestMatch % 10));
				for (int i = 0; i < countersLen; i++) {
					rowOffset += counters[i];
				}
				if (bestMatch >= 10) {
					lgPatternFound |= 1 << (5 - x);
				}
			}
			
			determineNumSysAndCheckDigit(resultString, lgPatternFound);
			
			return rowOffset;
		}
		
		int* UPCEReader::decodeEnd(Ref<BitArray> row, int endStart){
			return findGuardPattern(row, endStart, true, MIDDLE_END_PATTERN, sizeof(MIDDLE_END_PATTERN)/sizeof(int));
		}
		
		bool UPCEReader::checkChecksum(std::string s){
			return UPCEANReader::checkChecksum(convertUPCEtoUPCA(s));
		}
		
		
		void UPCEReader::determineNumSysAndCheckDigit(std::string& resultString, int lgPatternFound){
			for (int numSys = 0; numSys <= 1; numSys++) {
				for (int d = 0; d < 10; d++) {
					if (lgPatternFound == NUMSYS_AND_CHECK_DIGIT_PATTERNS[numSys][d]) {
						resultString.insert((size_t)0, (size_t)1, (char) ('0' + numSys));
						resultString.append(1, (char) ('0' + d));
						return;
					}
				}
			}
			throw ReaderException("determineNumSysAndCheckDigit exception");
		}
		
		/**
		 * Expands a UPC-E value back into its full, equivalent UPC-A code value.
		 *
		 * @param upce UPC-E code as string of digits
		 * @return equivalent UPC-A code as string of digits
		 */
		std::string& UPCEReader::convertUPCEtoUPCA(std::string upce) {			
			std::string result;
			result.append(1, upce[0]);
			char lastChar = upce[6];
			switch (lastChar) {
				case '0':
				case '1':
				case '2':
					result.append(upce.substr(1,2));
					result.append(1, lastChar);
					result.append("0000");
					result.append(upce.substr(3,3));
					break;
				case '3':
					result.append(upce.substr(1,3));
					result.append("00000");
					result.append(upce.substr(4,2));
					break;
				case '4':
					result.append(upce.substr(1,4));
					result.append("00000");
					result.append(1, upce[5]);
					break;
				default:
					result.append(upce.substr(1,5));
					result.append("0000");
					result.append(1, lastChar);
					break;
			}
			result.append(1, upce[7]);
			std::string& returnResult = result;
			return returnResult;
		}
		
		
		BarcodeFormat UPCEReader::getBarcodeFormat(){
			return BarcodeFormat_UPC_E;
		}
	}
}
